<!DOCTYPE html>
<html lang="en" xmlns="http://www.w3.org/1999/html">
    <head>
        <meta charset="UTF-8">
        <title>Title</title>
    </head>
    <body>
        <div id="app">
            <input type="text" v-model.lazy="money">{{money | dollar}}
            <input type="text" v-model="moneys">{{moneys}}
        </div>
        <script src="js/vue.js"></script>
        <script>
            let vueapp
            new Vue({
                el: "#app",
                data: {
                    money: "",
                    moneys: ""
                },
                beforeCreate(){
                    vueapp = this
                },
                filters: {
                    'dollar': (val1) => {
                        return vueapp.moneys + val1;
                    }
                }
            })
        </script>
    </body>
</html>